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Primitive Mollusc - Animals in the Habitats, and Biodiversity
The followings are extinct primitive molluscs excavated and extant primitive molluscs in the world. The explanation in brackets is the ages they lived in extinct species. Note that Mya is million years ago. For example, "48.6~40.4 Mya" shows a range between 48.6 and 40.4 million years ago. The time range is shown in the Geological Time Table. The followings are a part of the Evolutionary Tree.
- Kingdom Animalia
- Phylum Mollusca
- Class Hyolitha
- Class Polyplacophora (Chitons)
- Class Monoplacophora (Limpet-like organisms)
- Class Gastropoda (Abalone, Limpets, Conch, Nudibranchs)
- Subclass Archaeobranchia
- Subclass Eogastropoda
- Subclass Orthogastropoda
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 | Primitive shell |
Murchisonia (472~130 Ma; Great Dying③④),
Loxonema (460.5~199.6 Ma; Great Dying③) |
- Class Cephalopod (Squid, Octopus, Cuttlefish, Nautilus, Ammonite)
- Subclass Nautiloidea (Nautilus)
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 | Cephalopod |
Nectocaris (505 Mya),
Plectronoceras (501~490 Mya),
Endoceras (488.3~443.7 Mya),
Cameroceras (488.3~445.6 Mya; 9m),
Estonioceras (488~472 Mya),
Tarphyceras (478.6~443.7 Mya),
Lituites (466~418.7 Mya),
Orthoceras (479~203.6 Ma; Great Dying③),
Actinoceras (471.8~336 Mya),
Cyrtoceras (460.5~345.3 Mya),
Rayonnoceras (339.4~312 Mya) |
- Order Nautilida (Nautiluses)
- Subclass Ammonoidea (Ammonites)
- Order Ammonitida
- Suborder Ammonitina
- Suborder Ancyloceratina
- Suborder Phylloceratina
- Subclass Coleoidea (Squid, Octopus, Cuttlefish)
- Class Bivalvia (Clams, Oysters, Scallops, Mussels)
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